With five weeks to go before Election Day, Democrats are still waiting for Donald Trump to create the nationwide swell that would be necessary to put the Republicans’ House majority into play. House races are often late to engage but, thus far, the developments have been a mixed bag for Democrats, keeping sizable gains out of reach.

The lack of vulnerable Democrats — and the resiliency of many Republican incumbents in the face of an unpopular presidential nominee — could amount to a historic election in the House, but not in the way one might think. The cycle could produce the fewest number of House seats to flip party control in 60 years.

Arizona Rep. Martha McSally holds a 19-point lead over Democratic challenger Matt Heinz according to a new campaign internal poll. She won her seat by just 167 votes two years ago. (Bill Clark/CQ Roll Call File Photo)

New internal polls of Arizona's competitive House races suggest the state could be on track to maintain the delegation's current 5-4 partisan split.

A Democratic Congressional Campaign Committee poll released Wednesday gave Democrat Tom O'Halleran a 45 percent to 38 percent lead over Republican Paul Babeu in the tossup 1st District. Current Democratic Rep. Ann Kirkpatrick is running for Senate.

Sheriff Paul Babeu of Pinal County, Arizona, seen here at a Capitol news conference in 2010 with Sen. John McCain, won the Republican primary for the state's 1st District Tuesday. (CQ Roll Call file photo)

Updated Sept. 4 | In Arizona's tossup 1st District, Democrat Tom O'Halleran, a former Republican state senator, will face off against Pinal County Sheriff Paul Babeu in November.

Babeu easily beat five other Republicans in the primary in this eastern Arizona district, but he brings years of baggage to the race.

Democrats are focusing on more suburban districts, where they believe changing demographics are moving seats into the Democratic column, in their effort to regain the majority in the House. (Tom Williams/CQ Roll Call file photo)

As Democratic chances of taking back the House improve with the success of Donald Trump and Ted Cruz, party strategists are trying to figure out exactly how and where it’s going to happen. It’s not too difficult to see Democrats gaining 10, or even 20, seats in November, but gaining the 30 required for a majority is more difficult and will require Democrats winning a large swath of seats where Republicans are currently heavy favorites.

Winning the House majority is more than focusing on the presidential margin and allotting House seats to Democrats because of the strength of some GOP incumbents. For example, Democrats are not going to defeat Republican Rep. Frank A. LoBiondo this year, even though President Barack Obama won New Jersey’s 2nd with 54 percent, or win New Jersey’s 3rd (which Obama won with 52 percent), where wealthy GOP Rep. Tom MacArthur could easily outspend any challenger.